As you can see from the image below, the device will stay true to its roots incorporating the same design language as the previous models.

It has been previously speculated that the Moto Z3 Play will offer a tall 18:9-inch screen while abolishing the physical home button at the bottom. Well, the new render confirms that and we can clearly see the fingerprint sensor on the right side, just below the volume keys. However, it remains unclear what's the purpose of the button on the left. It could be a power button, but a dedicated Google Assistant key seems way more plausible.

Furthermore, the device will feature three microphones - two on the front and one on the back. This suggests of enhanced voice control or even an update to the current Moto Actions feature.

As it seems, the back of the device will be made of glass and the pins for the Moto Mods are here to stay but the same cannot be said about the 3.5 mm audio jack. The thinness of the device doesn't allow it.

We can't wait to see what the Moto Z3 Play has in store for us. Earlier rumors suggested a price tag of around $450, so we are curious to see what kind of hardware that will get you.

Yup e.g.
Qwerty slider https://www.indiegogo.com/projects/keyboard-mod-­a-physical-keyboard-for-the-moto-z
Others might be interested in other of the alternatives, with a limited market in them selves.
AND it is quite handy, that you can s...

Mods add to the cost. Its not like they sell for free, so you pay for phone + mod. And can you please tell me what can mods do that third party accessories can't? I do accept its a great idea and integration is pretty flawless, but it comes at hefty ...

I think you answered your own request. If they had made the "Play" model too powerful it would be too close to the "Force". They are trying to span a wider range of users with two distinct models.
Spec-wise the Z-series are expensive BUT they of...